A Mössbauer study of hemoglobin in paroxysmal nocturnal hemoglobinuria

The⁵⁷Fe Mössbauer spectra of concentrated hemoglobin (Hb) of normal subjects and six patients with Paraxysmal Nocturnal Hemoglobinuria (PNH) were studied at 300°K and 77 K. PNH is a very rare autoimmune hematological disease. The possibility of structural alterations of Hb induced by, or as part of the altered PNH-red cell membrane was the objective of this study. The Mössbauer parameters of the Hb of the normal subjects, both at 300 K and at 77 K, are identical to values previously reported. The PNH-Hb spectra show clear differences. They are wider and more asymmetric. At 77 K an extra doublet grows in with an isomer shift of 0.425 mm/sec. and a quadrupolar splitting, of 1.951 mm/sec. The other two doublets have δ′s and ΔQ's slightly, but significantly, different from the corresponding values for normal Hb. These results are rationalized in terms of a population of Hb molecules with structures varying very slightly in a narrow range. The spread in structures manifests itself in a wider and more asymmetric Mössbauer spectrum.